1. Field of the Invention
The invention relates to an inflatable packer assembly for use in a subterranean well.
2. Description of the Prior Art
Fluid pressure expandable elements have heretofore been employed in a number of applications, such as packers and seals for subterranean well bores. One effective structure for an inflatable packer embodies an annular array of elongated slats formed of a relatively rigid, yet deformable material, such as metal. The array of slats surrounds an elastomeric sleeve which is expanded by fluid pressure applied to the inside of the sleeve to force the resulting structure radially outwardly until it engages the inner wall of a surrounding element, such as a well bore. To improve the sealability of the expanded slat constructions, it has heretofore been suggested that an outer elastomeric sleeve be provided surrounding the slat structure which is concurrently expanded by the applied fluid pressure into sealing engagement with the well bore and held in such engagement by the deformed metallic slats. Constructions of this type are shown in U.S. Pat. Nos. 3,581,816 and 3,604,732 to Malone.
It has been observed, however, that when such inflatable element is employed as a packer for a substantial period of time, the outer elastomeric sleeve tends to cold flow or extrude in an axial direction. Unusually high temperature or pressure conditions produce a similar result. Such extrusion, if continued over a substantial period, will deleteriously affect the sealing engagement of the expanded element with the well bore or actually permit slippage of the expansion element under the weight of the production string or other tools attached to the expanded element when it is employed as a packer.